Assembly of hexa- and trinuclear monoorganostannoxanes: hemi-labile nature of intramolecular N→Sn coordination in RSnCl3 (R=2-phenylazophenyl)

The reactions of RSnCl3 [R = 2-(phenylazo) phenyl] with phosphonic acids, RPO3H2 (R = t-Bu, C6H11) or (ArO)(2)PO2H (Ar = 4-NO2-C6H5O) in refluxing THF afforded hexatin cages, [(RSn)(6)(mu-OH)(6)(mu(3)-O)(2)(t-BuPO3)(4)] center dot 5THF (1), [(RSn)(6)(mu-OH)(6)(mu(3)-O)(2)(C6H11PO3)(4)] center dot THF (2) and [(RSn)(6)(mu-OH)(4)(mu(3)-O) (2){(NO2C6H4O)PO3}(4)] center dot THF (3), respectively. On the other hand, the reactions of RSnCl3 with 1,1,2,3,3-pentamethylene phosphinic acid [cycPO(2)H] or Ph2P(O OH under similar reaction conditions afforded trinuclear O-capped clusters [(RSn)(3)(mu(3)-O) (mu(2)-OH)(3)(mu-cycPO(2))(3)] [cycPO(2)] center dot CH3CN center dot H2O (4) and [(RSn)(3)(mu(3)-O) (mu(2)-OH)(3)(mu-Ph2PO2)(3)] [Ph2PO2] center dot CH3CN center dot CH2Cl2 (5) respectively. Molecular structures of 1-3 reveal that the intramolecular N. Sn coordination found in RSnCl3 is hemilabile; 1-3 do not contain such a feature and the tin atoms in these compounds are six coordinate, possessing a 1C, 5O coordination environment in a distorted octahedral geometry. The cage structures in 1-3, containing two trinuclear sub-units, are formed as a result of the coordination action of several ligands: 4 mu(3)-(eta(1)eta(1)eta(1))[RPO3](2-), 2 mu(3)-O(2-)and 6 mu-OH. The molecular structures of 4-5 reveal them to be cationic trinuclear complexes where 3 tin and 4 oxygen atoms occupy the vertices of a distorted cube while one of the vertices is unoccupied. The molecular structures of 4-5 also reveal that the intramolecular N. Sn coordination present in RSnCl3 is absent in these compounds attesting to the hemilabile nature of this interaction.